Enzymeimmunoassay (EIA) has gained increasing importance as an analytical procedure during the last decade or so. These techniques combine the inherent sensitivity of the antigen-antibody reaction with the advantages of conventional enzymatic analysis. Representative descriptions of prior art EIA may be found in U.S. Pat. Nos. 4,134,792, 4,238,565 and 3,791,932 and in D. Woral et. al., Clin. Chem. 27(5), 673-677 (1981), That. T. Ngo et. al., J. Immunological Methods 42, 93-103 (1981) and A. J. O'Beirne and H. R. Cooper, J. Hist. Cytochemistry, 27(8), 1148-1162 (1979).
EIA is generally categorized into two major classes, homogeneous and heterogeneous enzymeimmunoassays. In homogeneous EIA, all the components are soluble in the test solution and are not separated prior to enzymatic activity determination. In heterogeneous EIA, either a solid phase component is utilized which allows the separation of bound from unbound components or a component of the initial solution is caused to precipitate and is subsequently removed from the solution. Such precipitation by prior art procedures is irreversible. In the prior art, kinetic enzyme analysis of the separated solid phase or precipitate was largely impractical due to limitations of solid phase reactions.